Biochemical studies of catecholamine metabolism in the adrenergic neurons of the rabbit oviduct will be extended to include estimation of the activity of tyrosine hydroxylase (rate-limiting enzyme for the synthesis of norepinephrine) and its cofactors at various times after ovulation in normal rabbits, in estrous and in castrated rabbits. Measurements will be made of the amount of NE released from isolated oviducts from similarly treated rabbits during stimulation of the adrenergic nerves. This will be done by incubating the tissue in 14C-tyrosine and then measuring the release of 14C-NE into the organ bath at various times after stimulation. The studies on the effects of nerve stimulated electrical activity of the smooth muscle cells will be continued with specific emphasis on the role of prostaglandins in the modulation of transmitter release at various times after ovulation.